1. Field of the Invention
The present invention generally relates to a system and methods for efficiently and safely transporting a quantity of lost circulation material to a predetermined location by employing a novel conveying system.
2. Background of the Related Art
In the field of drilling, drill rigs are typically of the rotary rig type. Rotary drill rig usually includes multiple engines that supply power hoisting equipment that raise and lower a drill string, and rotary equipment that turn the drill string and a drill bit attached to the end of the drilling string. These engines also power the circulation equipment that pumps drilling fluids down hole to lubricate the drill string and drill bit.
The drilling crew is under the supervision of a driller who operates the drilling and hoisting equipment. The person who works on a platform, high in the derrick, is called a derrickman. The derrickman's job is to handle the upper part of the drill stem as it is raised and lowered out/into the hole. The workers who work on the drill floor are called rig workers or roughnecks. Their job is to perform general labor and add new pipe joints as the well is drilled. All of these personnel and the entire operation of the drill rig is under the supervision of a person called a tool pusher. A typical drill rig will operate 24 hours per day, 7 days per week.
In the field of hydrocarbon exploration and more specifically, during the drilling of wells to recover oil and gas it is necessary to circulate the drilling fluid down the hollow drilling pipe to the bottom of the well bore and back up the well bore to the surface. This drilling fluid keeps the geologic formations (dirt, rock, voids, air pockets, etc.) surrounding the well bore in place and enhances and/or maintains the ability to move the drill pipe up and down within the well bore. Drilling fluids of different weights and viscosities are required depending upon the depth of the well, the geologic formations encountered and the diameter of the well bore. For example, in the Oklahoma and Texas panhandle, the dolomite and other underground geological formations are much more fractured than in other areas of the world. Such fractures lead or require a drilling fluid (and one preferably having a lost circulation material added thereto) capable of bridging and/or sealing off the fractured zone such that the drilling fluid is not lost through such fractures.
Operation of rotary drilling equipment involves rotating a drill bit by means of a hollow pipe. The drilling fluid circulates down the hollow pipe, through the bit, and back to the surface through the annular space between the outside of the drill pipe and the inside of the drilled hole or casing. The drilling fluid performs many functions in rotary drilling operations including, but not limited to: 1) remove formation cuttings from the drilled hole; 2) suspend cuttings during trips; 3) form an impermeable wallcake; 4) prevent caving of the formation; and 5) control of formation pressure.
Consequently during the drilling of an oil and gas well, it is necessary to continuously monitor the drilling fluid and change the physical characteristics and properties of the drilling fluid as new situations are encountered. These physical characteristics include the addition of lost circulation material. The function of lost circulation material (or “LCM”) is to seal off porous or fractured formations encountered while drilling oil and gas wells. In this manner, the LCM serves the purpose of filling in or “packing” the voids to ensure that drilling fluid is not lost or siphoned off through the voids and away from the well bore.
A typical drilling fluid system for an oil and gas well drilling rig includes a holding tank, usually positioned at the well surface (on or adjacent to the drilling rig) and a network of pumps, mixers, and supply lines that run to and from the well bore. In some situations, the holding tank may be positioned substantially adjacent the well bore. The location of the holding tank is thus widely variable and dependent upon historical preference and/or space limitations at the well site.
The holding tank is used to hold the various dry and liquid components of the drilling fluid as they are mixed into a slurry to produce a drilling fluid of the desired physical properties and characteristics. The drilling fluid is then pumped from the holding tank through the supply lines and circulated through the well bore at the desired rate.
The physical characteristics and properties of the drilling fluid are altered by the addition of liquids (such as water) powder and other types of lost circulation materials. Oftentimes, the drilling fluid is simply mud that has water or other materials added to it. These lost circulation materials are typically packaged in burlap or paper bags weighing up to one hundred pounds each. Bags of lost circulation materials are manually loaded in a storage area on the rig or at the well site in an out-of-the-way location. When needed, the bags of lost circulation materials are typically carried by the rig workers to the holding tank. The lost circulation materials are then manually dumped by the rig workers into the holding tank. Manually carrying and dumping the bags is physically demanding and oftentimes dangerous and fatiguing to the rig worker. Further, the method requires a significant amount of manpower to accomplish the task especially when it is necessary to rapidly add bags of lost circulation material to the drilling fluid to change its physical properties in response to an encountered geologic situation. There are many types of LCM utilized in the oil and gas industry. Examples of LCM's include: cottonseed hulls, cedar fiber, paper, cottonseed burrs, sawdust, cellophane, calcium carbonate, phenolic plastic, and many others. These lost circulation materials vary in size and bridging characteristics (i.e., their ability to lock together and not flow into and through the fracture). If a lost circulation material has a high bridging characteristic, its particles are typically of varying size and act similar or cause a cement like effect by filling up (i.e., bridging) the fracture thereby stopping any potential loss of drilling fluid. It is seldom known what size geologic voids or openings drilling fluid is being lost to. And, therefore, a mixture of particle sizes is more effective. Local availability or preference may also determine the lost circulation material used at any given location.
Because of the physical demands of lifting and carrying the bags of LCM, the rig workers are subject to physical injury and heat exhaustion. In addition, loading, carrying, and dumping of the bags may expose the rig worker to the dust and fumes generated by the dry powdered materials typically contained in the bags and may create a hazardous environmental risk to the rig workers. For example, the inhalation of LCM may be carcinogenic often time. Further, an environmental waste disposal problem is created by the used empty paper bags remaining after the lost circulation material is dumped in the mud system.
In addition to the physical and environmental risks associated with storing and handling lost circulation materials in bags, these types of bags impose significant storage problems at the drilling site. Bag storage typically requires a great deal of space, and storage space is especially valuable in a drilling installation where drilling platform space is finite and often quite limited. Consequently, sufficient bag storage space on a drilling rig is often unavailable or inconveniently located, especially in situations where it is necessary to have on hand, at the well site, a wide variety of different types of components available for use in the drilling mud system. Inconvenient storage space makes it especially difficult to manually move the bags from storage to the mud system. Therefore, a need exists for systems and methods of easily, efficiently and safely transporting lost circulation materials to the drilling fluid holding tank at a well site.